Kope Formation Research Articles

Factors Contributing to Landslide Susceptibility of the Kope Formation, Cincinnati, Ohio

ABSTRACT The objective of this study was to evaluate the factors that contribute to the high frequency of landslides in the Kope Formation and the overlying colluvial soil present in the Cincinnati area, southwestern Ohio. The Kope Formation consists of approximately 80 percent shale inter-bedded with 20 percent limestone. The colluvium that forms from the weathering of the shale bedrock consists of a low-plasticity clay. Based on field observations, LiDAR data, and information gathered from city and county agencies, we created a landslide inventory map for the Cincinnati area, identifying 842 landslides. From the inventory map, we selected 10 landslides that included seven rotational and three translational slides for detailed investigations. Representative samples were collected from the landslide sites for determining natural water content, Atterberg limits, grain size distribution, shear strength parameters, and slake durability index. For the translational landslides, strength parameters were determined along the contact between the bedrock and the overlying colluvium. The results of the study indicate that multiple factors contribute to landslide susceptibility of the Kope Formation and the overlying colluvium, including low shear strength of the colluvial soil, development of porewater pressure within the slope, human activity such as loading the top or cutting the toe of a slope, low to very low durability of the bedrock that allows rapid disintegration of the bedrock and accumulation of colluvial soil, undercutting of the slope toe by stream water, and steepness of the slopes.

Rare colonial corals from the Upper Ordovician Kope Formation of Kentucky and their role in ephemeral invasions in the Edenian

A large colonial rugose coral was recently discovered as float partially buried beneath several inches of sediment in the Kope Formation of northern Kentucky. Corals are unreported in the Kope assemblage, not appearing until much later during the C4 and C5 sequences during the Richmondian Invasion, a period in which the area was inundated with invasive taxa migrating from the midcontinent. The slab contains the remains of several other species that are diagnostic of the Kope Formation, such as the brachiopods Sowerbyella rugosa and Zygospira cincinnatiensis. The large colonial rugose coral is composed of corallites ranging in diameter from 3 to 5 mm containing 10–14 twisting major septa with crenulated walls, which is consistent with Cyathophylloides cf. C. burksae.New taxa or new occurrences in a well-sampled formation, such as the Kope Formation, are unexpected especially for large skeletonized taxa, and highlights the rarity of coral within the assemblage. The Richmondian Invasion is linked to a transgressive event that increased connectivity between marine biogeographic provinces, disrupted ecosystem structure as well as acted as a significant evolutionary driver during the late Ordovician in the Cincinnatian faunal assemblages. Isolated dispersal events may have brought planktonic larva onto the Cincinnati Arch much earlier during transgression in the C1 sequence. The failure of the coral to become established might be linked to the low abundance of larva entering the region or non-ideal environmental conditions. The discovery of this coral in the Kope Formation further indicates the occurrence of rare and ephemeral dispersal events that have recently been reported within brachiopods.

A noteworthy accumulation of disparid crinoids from the type Cincinnatian (Upper Ordovician) of southwestern Ohio, USA: implications for the palaeoecology and taphonomy of crinoid “logjam” assemblages

Crinoids are a common and well-studied faunal component of the Upper Ordovician (Katian; Edenian) Kope Formation in the greater Cincinnati Arch region, USA. However, a relatively fresh outcrop exposing the Southgate and McMicken members of the Kope Formation at Cleves, Hamilton County, southwestern Ohio, has yielded a crinoid specimen worthy of description and comment. The specimen is a “logjam” of numerous articulated columns of Iocrinus subcrassus displaying parallel alignment, reflecting the influence of storm-generated currents. Iocrinus is not typically found in such a state; the genera Ectenocrinus and Cincinnaticrinus are generally associated with “logjams” in the type Cincinnatian, making this an unusual occurrence. At least one of the columns has the coiled dististele of another, smaller I. subcrassus tightly wrapped around it. Although I. subcrassus is known to employ a coiled dististele as an attachment strategy, ramose bryozoans are generally utilised as substrates and tight coiling around larger I. subcrassus columns has not previously been reported. Preservation of coiled dististeles, in general, is a feature not previously documented in Cincinnatian crinoid “logjams.” This specimen illustrates that unusual, noteworthy and/or rare material representing relatively common organisms continue to be discovered even within extensively studied units in the type Cincinnatian.

Contrasting ecosystem impacts of biotic invasions in the Type Cincinnatian Series (Late Ordovician, Katian)

Species migration events are common features of the fossil record, but the impacts of immigration events vary. In this paper, the pattern and impact of two types of immigration events are compared: ephemeral invasion and biotic immigration events (BIMEs). Specifically, this study focuses on biotic patterns preserved in Edenian, Maysvillian, and Richmondian (Late Ordovician, Katian) age strata in the Cincinnati, USA region. New Edenian occurrences of rhynchonelliformean brachiopod taxa belonging to the classic “Richmondian Fauna” are documented, and the ecological and evolutionary impacts of these short-lived pre-Richmondian invasions and the sustained Richmondian Invasion are compared. The Richmondian Invasion produced substantial ecological changes and evolutionary impacts within the Cincinnatian paleocommunity; however, the ephemeral invasions that occurred in the Kope Formation did not produce a marked or lasting impact on ecological relationships within Cincinnatian paleocommunities. In each instance, an Edenian novel immigration or biotic event was limited in temporal duration and did not exceed the time to deposit a single sedimentary package. Although such ephemeral invasions do not result in community-scale changes, they nevertheless provide important information about basin connectivity, provide insight into abiotic environmental conditions, and can be useful stratigraphic indicators.

Chemical, mineralogical and textural properties of the Kope Formation mudstones: How they affect its durability

The Kope Formation is a rock unit that extends over southwest Ohio and adjacent areas of Kentucky and Indiana, USA. It is characterized by meter-scale cycles of mudstones and limestones where thick mudstone is sandwiched between thin limestone layers. Kope Formation mudstones are less durable than the mudstones in the area. They cause abundant slope failures in areas of their outcrops. This study evaluates chemical, mineralogical and textural properties of Kope mudstones to determine why it is less durable. The Two-cycle slake durability index (ID2) was measured on thirty mudstones belonging to three consecutive cycles of the Kope Formation. Chemical composition and mineralogy of Kope mudstones do not show significant relationship with the ID2. Instead, a relationship to fabric was found. Kope mudstones with two main fabric types were observed in the field; laminated mudstones and non-laminated mudstones. Detailed micro-fabric analysis on Kope mudstones was done using the scanning electron microscope. Laminated mudstones with turbostratic fabric showed higher ID2 and lower moisture content than the non-laminated mudstones with matrix fabric. The difference in the ID2 of laminated mudstones and non-laminated mudstones is statistically significant. Both mudstone types exist in many cycles of the Kope Formation. Thus, core samples should be selected from both types for preliminary tests in geotechnical practice, to obtain more accurate estimations of the geotechnical properties of the Kope mudstones. The results and data interpretations of this study can be correlated with the mudstones and shale in different areas of the world. Specifically, a great attention should be paid to the macro and micro textural properties of any rock type regardless of their classification.

INVERTED TRILOBITES: KEY TO COMPLEX PRESERVATION OF AN ORGANICALLY TEXTURED SURFACE IN OFFSHORE SILICICLASTIC MUDSTONE AND CARBONATE FACIES: KOPE FORMATION (UPPER ORDOVICIAN), KENTON COUNTY, KENTUCKY, USA

Abstract: Unusual preservation of small primaspid trilobites may provide a key to interpretation of an enigmatic, apparently organically textured surface or sedimentary structure in the subtidal Upper Ordovician (Katian) Kope Formation of northern Kentucky. A thin, elliptical lens of silty mudstone in the lower Kope Formation (Pioneer Valley submember, Southgate Member, C-1 Sequence) has several unique features mainly present on its basal surface, as a hyporelief, but also to a limited extent on the upper surface. Toward one end, the basal surface has sinuous fluting that terminates at the other end in a complex of conjoined, flattened, ellipsoidal or spatulate lobes that is partly overlain by an outlier of the primary lens. The basal surface has small-scale corrugations (3 to 4 mm wide) and polygonal reticulation variably developed. Articulated exoskeletons of small, spinose primaspid trilobites [Primaspis crosotus (Locke)] occur mostly with their ventral surfaces applied directly to the textured surface...

Eustatic and far-field tectonic control on the development of an intra-platform carbonate-shoal complex: upper tongue of the Tanglewood Member, Upper Ordovician Lexington Limestone, central Kentucky, U.S.A.

The Lexington or Trenton Limestone is an Upper Ordovician (Chatfieldian–Edenian; upper Sandbian–lower Katian), temperate-water unit, averaging about 60-m thick, that was deposited in relatively shallow waters across the Lexington Platform in east-central United States during the Taconian Orogeny. Lexington/Trenton shallow-water deposition ended across most of the platform in late Chatfieldian time and from that point deepened upward into the more shale-rich Clays Ferry, Point Pleasant and Kope formations due to apparent sea-level rise. In central Kentucky, however, deposition of the Lexington Limestone continued into early Edenian time and includes up to 50m of additional coarse calcarenites and calcirudites at the top, which form the Tanglewood buildup and reflect locally regressive conditions, apparently related to local structural uplift. Consequently, in central Kentucky, the Lexington is more than 100-m thick, and Lexington deposition on the buildup continued into early Edenian time as an intra-platform shoal complex that tongues out into deeper-water units in all directions. In an attempt to understand how this shoal complex developed, we examined the last major body of coarse skeletal sands in the central Kentucky Lexington Limestone, the upper tongue of the Tanglewood Member, a 12-m-thick succession of fossiliferous calcarenite and calcirudite that occurs across an area of 5200km2 near the center of the Lexington Platform. Although relatively homogeneous, the upper Tanglewood is divisible into five, small-scale, fining-upward, sequence-like cycles, which contain prominent, widespread deformed horizons. Facies analysis indicates that four lithofacies, which reflect distinct depositional environments, comprise the sequences across the shoal complex. Lithofacies were correlated across the shoal complex by integrating cyclicity and widespread deformed horizons in order to delineate the locations of major depositional environments. Facies analysis shows that the thickest and coarsest parts of each sequence, and the shallowest depositional environments, coincide with basement fault blocks, which are known to have experienced uplift during earlier Lexington Limestone deposition. The occurrence of thick, coarse facies on the same blocks suggests that the blocks continued to experience uplift into shallow water, where tides and waves redistributed sediments during upper Tanglewood deposition. Although eustasy apparently controlled cyclicity, Taconian far-field forces generated by orogeny in the east seem to have influenced facies distribution in each cycle through reactivation of basement fault zones as synsedimentary growth faults. The example of the upper Tanglewood Member shows that tectonic far-field forces can exert important influences on the development of carbonate depositional environments, even in distal intracratonic settings like the Lexington Platform.

Siltstone: a key to cyclicity in mixed siliciclastic–carbonate successions: example from Upper Ordovician Kope Formation (Ohio, Indiana, Kentucky)

The Upper Ordovician (mid-Katian) Kope Formation provides an example of how a detailed study of fine-grained siliciclastic sediment can provide sedimentological insights. The Kope Formation is an exemplar of mixed siliciclastic–carbonate cyclicity; however, most of the sedimentological research to date has focused on the fossiliferous limestone beds. Conversely, this paper provides a detailed investigation of siltstone within 42 metre-scale cycles from 26 locations spanning a large geographic area. The objective of the study is twofold: (i) to confirm the mineralogical nature of silt-sized sediment. Currently, silt-sized sediment is irregularly defined as being either carbonate or siliciclastic rich. This paper uses X-ray diffraction, thin-section, and elemental analyses to determine the mineralogy of the silt; (ii) to determine the stratigraphic distribution of siltstone beds. If a distinctive and reoccurring distribution of siltstone can be found, then it can provide additional information about environmental energy changes that led to cyclic fossiliferous limestone formation. This study finds that silt within the Kope Formation is siliciclastic and siltstone, therefore, records periodic minor pulses of coarser terrigenous sediment. Predominantly, metre-scale limestone–shale cycles show an increasing abundance of siltstone beds in the upper half of the shale interval, with a marked decrease just before the capping limestone. This finding supports the idea that limestone formation occurred during slowing sedimentation, perhaps at a time of maximum sea-level rise. Furthermore, decametre-scale fluctuations in siltstone abundance are similar in pattern to previously documented faunal variations, indicating that fauna assemblage might be more controlled by turbidity and not depth.

General models of ecological diversification. II. Simulations and empirical applications

AbstractModels of functional ecospace diversification within life-habit frameworks (functional-trait spaces) are increasingly used across community ecology, functional ecology, and paleoecology. In general, these models can be represented by four basic processes, three that have driven causes and one that occurs through a passive process. The driven models include redundancy (caused by forms of functional canalization), partitioning (specialization), and expansion (divergent novelty), but they also share important dynamical similarities with the passive neutral model. In this second of two companion articles, Monte Carlo simulations of these models are used to illustrate their basic statistical dynamics across a range of data structures and implementations. Ecospace frameworks with greater numbers of characters (functional traits) and ordered (multistate) character types provide more distinct dynamics and greater ability to distinguish the models, but the general dynamics tend to be congruent across all implementations. Classification-tree methods are proposed as a powerful means to select among multiple candidate models when using multivariate data sets. Well-preserved Late Ordovician (type Cincinnatian) samples from the Kope and Waynesville formations are used to illustrate how these models can be inferred in empirical applications. Initial simulations overestimate the ecological disparity of actual assemblages, confirming that actual life habits are highly constrained. Modifications incorporating more realistic assumptions (such as weighting potential life habits according to actual frequencies and adding a parameter controlling the strength of each model’s rules) provide better correspondence to actual assemblages. Samples from both formations are best fit by partitioning (and to lesser extent redundancy) models, consistent with a role for local processes. When aggregated as an entire formation, the Kope Formation pool remains best fit by the partitioning model, whereas the entire Waynesville pool is better fit by the redundancy model, implying greater beta diversity within this unit. The ‘ecospace’ package is provided to implement the simulations and to calculate their dynamics using the R statistical language.

Deepwater occurrence of a newGlyptocrinus(Crinoidea, Camerata) from the Late Ordovician of southwestern Ohio and northern Kentucky: revision of crinoid paleocommunity composition

AbstractA new crinoid association reported from the Kope Formation (Katian, Ordovician) of northern Kentucky and southwestern Ohio changes the model for facies distribution of crinoids along an Ordovician onshore-offshore depth gradient.Glyptocrinus nodosusn. sp.,Plicodendrocrinus casei(Meek, 1871),Cincinnaticrinus varibrachialis(Warn and Strimple, 1977), andEctenocrinus simplex(Hall, 1847) are reported from a suspension-feeding assemblage with 26 taxa. This assemblage developed above an argillaceous packstone with most of the fossils preserved in shale. The fauna was comprised principally of secondary epifaunally tiered suspension feeders, deposit feeders, and predators. This is the first reported occurrence ofGlyptocrinusHall, 1847 andPlicodendrocrinusBrower, 1995 from the Kope Formation (lower Cincinnatian), andGlyptocrinusis represented by a new species,G.nodosus. Also, this is the first report of pinnulate camerate crinoids from the deep-water facies of the Kope Formation. Thus, deep-water Cincinnatian crinoid assemblages were comprised of disparids, cladids, and camerates; and the assemblage was characterized by a variety of filtration fan types for acquisition of resources.

Visual identification and quantification of Milankovitch climate cycles in outcrop: an example from the Upper Ordovician Kope Formation, Northern Kentucky

Abstract Applying time-series analyses using Fourier transform and multi-taper methods to low-field, mass-specific magnetic susceptibility (χ) measurements on marine samples from well-studied shale and limestone outcrops of the Upper Ordovician (Edenian Stage; Upper Katian) Kope Formation, northern Kentucky, corroborates direct visual identification in outcrops of Milankovitch eccentricity ( c. 405 and 100 ka), obliquity and precessional climate cycles. Because individual outcrops were too short and deposition too chaotic to yield significant time-series results, it was necessary to build a c. 50 m thick composite sequence from three well-correlated outcrops to quantify the cyclicity. Time-series analysis was then performed using χ measured for 1004 closely spaced samples covering the section. Milankovitch bands are recorded in the time-series data from the composite. We tested this result by comparison of these bands to cyclic packages in outcrop, which correspond to thicknesses represented in the time-series datasets. This is particularly well defined for the eccentricity and obliquity cycles, with precessional bands being evident but as less well-defined packages of beds.

Record of microendoliths in different facies of the Upper Ordovician in the Cincinnati Arch region USA: The early history of light-related microendolithic zonation

This study provides the first documentation of microendolithic borings made by cyanobacteria, algae, and fungi in invertebrate skeletons from the Late Ordovician of eastern North America. Samples from the upper Mohawkian to Cincinnatian Series (Katian Stage, Caradoc to lower Ashgill of traditional usage) limestones and calcareous shales of Ohio, Indiana, and Kentucky were selected for study, because of the excellent preservation of fossil shell material; the substrates mostly are brachiopods and corals. Strata of the Mohawkian Lexington Limestone and Cincinnatian Kope Formation, Maysville, and Richmond Groups have been recently studied in terms of facies, sequence stratigraphy, and paleoenvironments, which facilitates a reliable comparison of the distribution of microborings and inferred environmental settings, especially relative paleobathymetry. This paper reports the first occurrence of 10 ichnospecies plus various Conchocelis traces in Late Ordovician (Cincinnatian) marine shells. These traces have been previously observed in shells from younger geological periods. Their modern counterparts are produced by species of cyanobacteria, green algae, red algae and heterotrophic microendoliths. Considering the bathymetric index ichnocoenoses of microendoliths defined for the later Phanerozoic, it appears that only one or two light-related bathymetric zones can be recognized in a few samples from the Upper Ordovician (Cincinnatian) of Ohio and Kentucky (but not in all deposits where they might have been expected): the Shallow Euphotic Zone III and — with less certainty — the Deep Euphotic Zone. On the contrary, our samples from the underlying Lexington Formation contain only borings of “worms” (Macrotubular Form) and some forms with unknown producers, although they were collected in facies realms comparable to the younger samples. Given the present state of knowledge, the best explanation for the appearance of these 10 ichnospecies and the first bathymetric index ichnocoenoses within the Late Ordovician is that they represent the early evolution of microendolithic ichnospecies and early emplacement of ichnocoenoses.

Subsurface Correlation and Paleogeography of a Mixed Siliciclastic-Carbonate Unit Using Distinctive Faunal Horizons: Toward a New Methodology

Abstract Regional correlation of mudrock-siliciclastic units is challenging, largely owing to the apparent featurelessness of fine-grained intervals. This difficulty is multiplied when subsurface correlation is necessary for paleogeographic reconstruction. In this study, faunal-marker tracing and limestone-pattern matching have permitted subsurface correlation of the Alexandria submember of the Kope Formation (Edenian Stage, Upper Ordovician) over a 193-km transect in southwest Ohio. The faunal markers are thin (<10 cm), widespread deposits of skeletal debris exhibiting faunal associations, degrees of preservation, or both, that distinguish them from other fossil deposits in host mudrocks. Subsurface correlations corroborate interpretations of southwest Ohio paleogeography and demonstrate the usefulness of techniques presented here. Geographic trends in the data indicate that the average seafloor slope over much of the Cincinnati region was near zero. Evidence also indicates a northwest-dipping paleoslope...

Analysis of sample-level properties along a paleoenvironmental gradient: The behavior of evenness as a function of sample size

The assessment of fossil biodiversity is influenced by a range of sampling effects such as sample size, evenness and lithological character. Many paleontologists have worked to understand and mitigate for such biasing effects, generating standardized assessments of local, regional and global biodiversity. However, when assessing biodiversity among individual communities with small sample sizes, such as those from lithified Paleozoic samples, it is important to understand how these properties relate to one another qualitatively and quantitatively. Here, the properties of richness and evenness were investigated at the sample level along an ecological gradient within a stratigraphically and geographically constrained interval, the Fulton submember of the Kope Formation (Upper Ordovician) of Kentucky and Ohio. Using a replicate subsampling procedure analogous to rarefaction, evenness values were generated using four metrics ( J, PIE, E ss and E ssmin). Simulations using real and simulated data revealed that the PIE metric generates the most stable assessments of evenness at very small sample sizes, and relative evenness can be assessed at any sample size, provided that replicate subsampling is performed. Comparisons of richness, evenness and lithology revealed no directional trend along the ecological gradient, but two distinct groups of samples were identified by differences in evenness as well as the number of sampled individuals. Such differences in abundance structure influence perceptions of biodiversity when samples from low-evenness and high-evenness assemblages are aggregated. Increasing the sampling intensity in low-evenness communities may help to mitigate for these differences and more thoroughly capture the richness contained within small samples.

Magnetostratigraphy susceptibility of the Upper Ordovician Kope Formation, northern Kentucky

As a test of the utility of magnetic susceptibility (MS) measurements for correlation among lithified marine sequences, samples were collected from well-studied shale and limestone outcrops of the Upper Ordovician Kope Formation, northern Kentucky. The bulk (initial) low-field MS of these samples is compared among two litho- and biostratigraphically correlated sections containing the same beds. The results of this comparison demonstrated an excellent correlation among equivalent beds. Thermomagnetic susceptibility analysis supports previous XRD work indicating that illite is primary and is the main paramagnetic mineral responsible for the MS variations observed in this study. A composite of MS results for a sequence of 31 named shale–limestone couplets is used to build a composite section of Kope sequences for the area. These MS variations permit division of the various sections into a set of 28 MS cycles within the Kope Formation, covering ∼ 50 m of section. These cycles suggest a systematic control by climate on the influx of detrital material that formed these sedimentary sequences, and support other work indicating Kope climate cyclicity.

Trilobite Taphonomy and Temporal Resolution in the Mt. Orab Shale Bed (Upper Ordovician, Ohio, U.S.A.)

Clay-rich units, locally termed ‘‘butter shales,’’ contain the best-preserved trilobites in the richly fossiliferous Cincinnatian Series and likely provide the highest temporal resolution available within these rocks. Sedimentological and taphonomic evidence indicates that the 0.46-m-thick Mt. Orab ‘‘butter shale’’ bed of the Arnheim Formation is composed of a series of stacked event beds, each representing rapid deposition from a flow bearing fine-grained sediment, most likely associated with distal storm processes below storm-wave base. It contains sedimentary structures similar to those of distal mud turbidites, and comprises a total of at least seven, and possibly many more, alternating silt and clay couplets. These clay and silt layers are interpreted to represent the products of different energetic regimes in a series of discrete depositional events accumulated within a common depositional regime. Trilobites within individual clay beds represent census assemblages of animals alive at the same time, and evidence from sedimentology, taphonomy, and stratigraphic architecture are consistent with accumulation of the whole bed within a period from 10 1 to 10 3 years. Silt layers of the Mt. Orab events beds are interpreted to represent parautochthonous assemblages, while clay layers, although displaying reorientation of specimens, are interpreted as autochthonous assemblages. Both layers are deposited in a shallower-water environment than the comparable ‘‘granulosa’’ trilobite cluster of the Kope Formation, which represents an autochthonous assemblage with in-situ burial of trilobites.

Comment--A New Angle on Strophomenid Paleoecology: Trace-Fossil Evidence of an Escape Response for the Plectambonitoid Brachiopod Sowerbyella rugosa from a Tempestite in the Upper Ordovician Kope Formation (Edenian) of Northern Kentucky (Dattilo, 2004)

In his recent article, Dattilo (2004) suggested that strophomenide brachiopods, in particular the plectambonitoid Sowerbyella , were capable of active locomotion, and even burrowing. The article argues that Sowerbyella was capable of living quasi-infaunally and upright, with the shell edgewise—a position that could be obtained by burrowing. As Dattilo summarizes, the consensus view (Rudwick, 1970; Richards, 1972; Alexander, 1975; Alexander and Scharpf, 1990; Leighton and Savarese, 1996; Leighton, 1998) of strophomenide life-position is that relatively immobile strophomenides lived convex-valve down. Dattilo notes that the primary argument of these studies was based on functional tests and conclusions, but that these studies assumed that the free-lying strophomenides were incapable of extensive movement. Dattilo, however, points out that if this assumption of relative immobility is incorrect, then strophomenides would be capable of achieving any orientation. As such, hypotheses that concavo-convex brachiopods lived with the convex-valve up (Lescinsky, 1995) would be plausible, and Dattilo argued that the epibiont-distribution data presented by Lescinsky, supporting a convex-valve up orientation, has not been refuted. Dattilo further suggests that Lescinsky's data were dismissed (Leighton, 1998) on the grounds of functional considerations (i.e., strophomenide immobility) that are not necessarily valid. This brings up an important point about the nature of functional evidence. Functional morphology has a poor reputation because many functional studies have been relatively sparse in data; functional hypotheses were often analogous to Kiplingesque “just-so” stories (Gould and Lewontin, 1979). It is interesting that the convex-up versus convex-down debate seemed to be indicative of a more modern approach to functional morphology in paleontology. For the past 35 years there has been a series of studies using two primary approaches for addressing orientation questions in the fossil record: epibiont distribution and biomechanical experiments. Both approaches aim to test functional plausibility. Both methods are valid. …

The Signatures of Patches and Gradients in Ecological Ordinations

Ordination is a common tool for reconstructing paleoecological gradients for ordering samples and taxa along one or more axes of variation in faunal composition. The primary source of variation, known as the primary gradient, commonly is highly correlated with water depth in marine systems, and elevation or moisture in terrestrial systems. When ordination sample scores are plotted stratigraphically, they commonly reveal long-term patterns of variation related to changes in this primary gradient, and these patterns have proved useful in regional correlation. In addition, ordination scores display high-frequency, high-amplitude patterns of variation unrelated to this primary gradient. The origin of this high-frequency variation has been enigmatic, but recently has been argued to reflect faunal patchiness. Numerical modeling of ordination scores derived from the Upper Ordovician Kope Formation of the Cincinnati, Ohio area is used here to demonstrate that such high-frequency patterns of variation indeed can arise from the presence of faunal patchiness along ecological gradients. The magnitude of this variation is controlled by the peak-abundance distribution of fossil taxa as well as the abundance distribution of a taxon at any given position along the primary gradient. Replicate sampling or moving averages should be employed to control for this high-frequency variation before ordination sample scores can be treated as a suitable proxy for environmental factors such as water depth, elevation, or moisture.

The Effects of Spatial Patchiness on the Stratigraphic Signal of Biotic Composition (Type Cincinnatian Series; Upper Ordovician)

Abstract Patchiness affects fine-scale patterns of biological variation because compositional differences among localities depend on the composition of the patch sampled for paleoecological analysis. This can inflate compositional differences among localities that otherwise may have similar faunal constituents, which can obscure the true signal of biotic composition. In the type Cincinnatian Series, comparisons of fine-scale faunal-assemblage patterns acquired through gradient analysis have been difficult to accomplish because of significant deviations in biotic composition. Here, the role of patchiness in creating these deviations is tested by quantifying the amount of lateral variation in composition at a single outcrop of the Kope Formation. Because the lateral expression of individual beds in the Cincinnatian is variable, patchiness is more effectively assessed for bedsets rather than individual beds. Using gradient analysis to evaluate lateral variation at one locality reveals that patchiness is the ...

A New Angle on Strophomenid Paleoecology: Trace-Fossil Evidence of an Escape Response for the Plectambonitoid Brachiopod Sowerbyella rugosa from a Tempestite in the Upper Ordovician Kope Formation (Edenian) of Northern Kentucky

Other| August 01, 2004 A New Angle on Strophomenid Paleoecology: Trace-Fossil Evidence of an Escape Response for the Plectambonitoid Brachiopod Sowerbyella rugosa from a Tempestite in the Upper Ordovician Kope Formation (Edenian) of Northern Kentucky BENJAMIN F. DATTILO BENJAMIN F. DATTILO 1Department of Geoscience University of Nevada-Las Vegas, 4505 Maryland Parkway, Box 45010, Las Vegas, NV 89154-4010, dattilob@unlv.nevada.edu Search for other works by this author on: GSW Google Scholar Author and Article Information BENJAMIN F. DATTILO 1Department of Geoscience University of Nevada-Las Vegas, 4505 Maryland Parkway, Box 45010, Las Vegas, NV 89154-4010, dattilob@unlv.nevada.edu Publisher: SEPM Society for Sedimentary Geology Accepted: 20 Feb 2004 First Online: 03 Mar 2017 Online ISSN: 1938-5323 Print ISSN: 0883-1351 Society for Sedimentary Geology PALAIOS (2004) 19 (4): 332–348. https://doi.org/10.1669/0883-1351(2004)019<0332:ANAOSP>2.0.CO;2 Article history Accepted: 20 Feb 2004 First Online: 03 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation BENJAMIN F. DATTILO; A New Angle on Strophomenid Paleoecology: Trace-Fossil Evidence of an Escape Response for the Plectambonitoid Brachiopod Sowerbyella rugosa from a Tempestite in the Upper Ordovician Kope Formation (Edenian) of Northern Kentucky. PALAIOS 2004;; 19 (4): 332–348. doi: https://doi.org/10.1669/0883-1351(2004)019<0332:ANAOSP>2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyPALAIOS Search Advanced Search Abstract A uniquely preserved occurrence of the plectambonitoid brachiopod Sowerbyella rugosa from the Upper Ordovician of Northern Kentucky shows several individuals preserved in direct association with burrow-like structures and oriented with the commissural plane vertical and the hinge line down in the upper laminated siltstone of a tempestite bed. Two types of structures are present: (1) structures that document translational motion of convex-up brachiopods to the surface, then rotation to a vertical position with the commissure near the sediment-water interface; and (2) structures that show slightly longer-term occupation and sediment clearing around the brachiopods before they expired in the post-storm accumulation of fine mud. The abilities demonstrated by these individuals require a rethinking of the helpless-strophomenid paradigm. The peculiar plectambonitoid traits, mantle threads (as evidenced by interarea canals) and external mantle flaps (as evidenced by comae) were unlikely to have contributed to the ability of these individuals to burrow upward. Valve clapping is the only apparent means by which Sowerbyella rugosa could have moved through the sediment. If plectambonitoids could have moved by clapping their valves, then the same may have been true of strophomenoids, such as Rafinesquina alternata. The ability to move sediment and adjust position explains how strophomenids could live in a convex-up position or even, if partially buried, in more vertical positions, as documented by previous epibiont studies. These abilities suggest that geniculation may have served to anchor shells of active individuals in an inclined or vertical position in higher-energy environments of shifting substrates rather than to lift commissures of passive individuals in a convex-down position in lower-energy environments of rapid mud accumulation. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.